replace powerpoint with text

The "powerpoint" imagery doesn't cover most cases, and being specific to a file format is weird. I like the "screen" one in the pro pack, but if we don't go with that, I'd prefer "document".

Author: bridgetkromhout

layouts/program/single.html

@@ -114,7 +114,7 @@ <h5 class="mb-0">
 
                               </a>
                               {{- with ($.Scratch.Get (printf "%s-video_link" .title)) -}}<a href="{{ . }}"><i class="fa fa-video-camera" aria-hidden="true"></i></a>&nbsp;{{- end -}}
-                              {{- with ($.Scratch.Get (printf "%s-slides_link" .title)) -}}<a href="{{ . }}"><i class="fa fa-file-powerpoint-o" aria-hidden="true"></i></a>&nbsp;{{- end -}}                                
+                              {{- with ($.Scratch.Get (printf "%s-slides_link" .title)) -}}<a href="{{ . }}"><i class="fa fa-file-text-o" aria-hidden="true"></i></a>&nbsp;{{- end -}}                                
                               <br/>
                               <br/>
                                 {{- if .comments -}}